Question: 6 binders cost $4.92. Which equation would help determine the cost of 7 binders?
Explanation: There are several equations that could help determine the cost, each with a slightly different approach. We can write the fact that 6 binders cost $4.92 as a proportion: $\dfrac{6}{\$4.92}$ Let $x$ represent the unknown cost of 7 binders. Since 7 binders cost $x$ , we have the following proportion: $\dfrac{7}{x}$ The cost changes along with the number of binders purchased, and so the two proportions are equivalent. $\dfrac{6}{\$4.92} = \dfrac{7}{x}$